1. Field of the Invention
The present invention relates generally to a face image capturing apparatus for capturing a face image of a driver.
2. Description of Related Art
A driver monitoring apparatus is known to use sensing means for acquiring a face image of a driver to detect an unfavorable state of the driver during driving operations, such as drowsiness and an inattentive driving. The above driver monitoring apparatus is required to reliably capture the face images regardless of a time, such as daytime or nighttime. Thus, conventionally, light including near infrared light is applied from an illuminator to a face of the driver as reference light such that a reliable situation for capturing the face images is established. Then, the face image captured under the above situation is processed through image processing such that the face of the driver is detected and a face part is detected.
However, in fact, because of the adverse influence by the sunlight, a reflected light by buildings, and reflection of the light from the illuminator reflected by eyeglasses of the driver, the image processing may be difficult to be sufficiently performed and also the above detection may not be achieved disadvantageously.
To address the above disadvantages, a technique described in JP-A-2002-352229 corresponding to U.S. Pat. No. 6,952,498 captures the images of a face portion of the driver when the driver is applied with illumination from two directions and reflected images are removed from the captured images to detect a retina reflected image. In the above, the reflected image in one of the captured images is located at a position different from a position of the reflected image in the other one of the captured images, and the above reflected images are determined as images that correspond to a glossy reflective surface of the eyeglasses.
In the above technique described in JP-A-2002-352229, the image that is free of the reflected image reflected by the glossy reflective surface may be acquired, however, the influence by ambient light, such as the sunlight, may not be removed.